The present invention relates to a semiconductor device and can be suitably used for, particularly, a system controlling circuit of a microcomputer.
A system controlling circuit which is mounted within a microcomputer or the like is a circuit block that supplies, inter alia, a power supply, reset signal, and clock across an LSI (Large Scale Integrated). This circuit controls, inter alia, timing of supply to functional blocks within the LSI. The circuit may control the supply and stop of a power supply and clock to the functional blocks or may control a power supply voltage and a clock frequency to be supplied. To perform such control properly, sequence and timing are important and customized on a per-product basis. This poses a problem that a period required for verification, TAT (Turn Around Time), is long in designing a system controlling circuit. Moreover, specifications that sequence and timing should meet may be restricted or changed due to coordination with other parts which are externally coupled to the LSI. Therefore, in an initial phase of developing a system controlling circuit, determining specifications tends to delay in comparison with other functional blocks. In a later phase of its development, specification change of parts which are externally coupled gives rise to re-verification of some verification items or additional verification items. Consequently, these things would be a cause of elongating the TAT of developing the entire chip. Along with an increasing need to decrease the power consumption of LSI in late years, there is a tendency in which a system controlling circuit is required to adapt to specifications for more elaborate control. Thus, a programmable specification change technique is needed for a system controlling circuit.
In Japanese Published Unexamined Patent Application No. 2013-89060, a start-up sequence controlling device for a power supply system is disclosed. The start-up sequence controlling device includes an analog-digital converter that converts a voltage value which is input from a terminal into a digital value and a register that retains a converted digital value and controls a power supply circuit according to start-up sequence or shutdown sequence which is determined by a digital value retained in the register.